Antirotational mechanism for floating tank roofs



June 6, 1944. J. H. WIGGINS 2,350,483

ANTIROTA'I'IIONAL MECHANISM FOR FLOATING TANK ROOFS Filed May 9; 1942 2 Sheets-Sheet 1 INVENTOR; JOHN H. WIGGINS- ATTORNEY June 6, 1944'. J. H. WIGGINS 2,350,433

ANTIRQTATIONAL MECHANISM FOR FLOATING TANK ROOFS Filed May 9, 1942 2 Sheets-Sheet 2 INVENT'OR HN H. W/GG/NS jfwaf H TTOB NE Y Patented June 6, 1944 OFFICE ANTIROTATIO NAL MEGHANISM FORv FLOATING TANK-RQQFS John H. Wiggins, Chicago, Ill.

Application May 9', 1942, Serial No. 442,327

1 Claim.

This invention relates to floating tank roofs,

and particularly tothe means used in suchstructures for preventing the roof from rotating or turning relatively to the side wall of the tan-k as the roof rises and falls in the tank. The main object of my invention is to elimihate or overcome the necessity of using co-acting rigid guiding devices on the tank side wall and on the floating roof or the seal at the peripheral edge of the roof, for preventing the roof from turning or rotating in the tank.

Another object is to provide an anti-rotational mechanism for floating tank roofs, which is of such design or construction that (a) there are no parts of said mechanism '10- cated'beneath the roof (b) there is no part of said mechanism that extends through a hole in the roof; and (a) there are no parts of said mechanism which engage, pass through or interfere with the operation of the side wall seal .at the peripheral edge of the roof.

Another object is to provide ,an anti-rotational mechanism for floating tank roofs, which, in addition to having the desirable characteristics above mentioned, is inexpensive to construct and easy to install.

To this end I have devised .an anti-rotational mechanism, which is ofsuch design or construction that in the event the roof starts to turn, even slightly, in either clockwise or counterclockwise direction, said mechanism will automatical- 1y check the rotary movement of the roof and restore it to its former position before therooi has moved far enough to interfere with the operation of any parts of the structure which might be injuriously affected by turningor rotary movement of the roof. In my improved .antirotational mechanism I do not depend upon rigid ,guideways on the tank that receive or co-act with rigid. guiding devices on the roof to hold the roof against rotary movement, but instead, I arrange the roof in the tank in such a way that it is capable of turning or rotating slightly in either direction, and I maintain or hold the roof in a certainapproximate position with relation to the side wall of the tank, by subjecting the roof to the action of opposing forces that counteract the tendency of the roof to turn clockwise orcounterclockwise, Under normal conditions, said opposing forces are balanced or substantially equal, but in the event an extraneous force is exerted .on the roof, in a direction tending to turn the roof, said opposing forces become unbalanced and one of said forces becomes magnified, enhanced, or increased 55.

sufliciently to resist and overcome the extraneous force-that caused the roof tostartto turn, thereby causing the roof to "be restored to its former position. If the roof starts to. turn in a clockwise direction, my improvedmechanism automatically checks the movement of the roof and moves the roof counterclockwise back to its former position. Similarly, if the roof starts to turn in counterclockwise direction, my improved mechanism automatically checks the movement of the roof and moves it clockwise back to its former position.

The mechanism can 'be constructed in various ways without departing from the spirit of my invention, "but it preferably comprises two flexible members attached to the roof and leading upwardly from the peripheral edge of same adjacent the sidewall of the tank, and a means that coacts with said flexible members to normally hold them under tension, said flexible members and means being .so constructed and arranged that said flexible members normally oppose or resist rotary movement of the roof in either direction, but in event the roof starts to turn, due to some extraneous force that is exerted on the roof,- the pull or force exertedby one of said flexible :members on the roof, will be decreased or eliminated, and the pullor force exerted by-the other flexible member onthe roof, will be increased orenhanced sufliciently to overcome the extranous turning forces exerted on the roof and move the roof back to its former position. The side wall of the tank carries a guiding or supporting means over which said flexible members travel, and the means that holds said flexible members under tension, may consist'of a weight, spring, or equivalent tension-producing device attached to or combined with said flexible members in such away that when the roof is in its normal position, the power, force, or pressure produced by said device is divided or applied, onehalf to one of said flexible members, and onehalf to the other flexible member, but whenever an extraneous 'forceis exerted on the roof sufficiently to .cause thereof tostart to turn or move away from-"its normal position, all of the power, force, or pressure produced by said device isexertedon only one'of said flexible members, i. e., the one that opposes the extraneous force that caused the roof to start to turn. Thus, it will be seen that in my improved anti-rotational mechanism, the opposing forces :that counteract the. tendency ,of the roof to turn or rotataare balanced or substantially equal when. the root is in its normal position, and movement of the roof away from its normal position automatically unbalances said opposing forces and increases or enhances the force that resists the movement of the roof in the direction in which it starts to turn.

In the preferred form of my invention herein illustrated, the flexible members, which may consist of chains or cables, are attached to the top side of the roof atseparated,points,.and are so disposed-that they lead {upwardly 'trom the roof and converge, or approximately converge, at an overhead guiding or supporting means on the tank;

side wall, located substantially mid-way the two separated points of attachment of the sexing the tank side wall, and are attached to a counterweight 2 that holds said flexible members under tension and causes said tension members to exert opposed forces on the roof and cause the roof to remain in a certain approximate position with relation to the side Wall of the tank. In the preferred form of my invention herein illustrated the guiding and supporting means C comprises a mast 3 that projects upwardly from the top edge of the side wall A of th tank, and a horizontally-disposed cross support 4 attached to the upper end of said mast and arranged so as to project some distance inwardly and some distance outwardly beyond the side wall of the tank, as

shown in Figure 2. At the inner end of said horizontally-disposed support 4 is a flared guide or bell '5', and at theouter end of said support 4 .i .there isa sheave or roller 6. The flexible memtional view of my improved anti-rotational mechanism, lookingat the inner face of the sidewall of the tank and showing the roof in'section.

Figure 2 is a fragmentary vertical sectional view, taken transversely'through the sid wall of the tank, a portion of the roof .being shown in vertical section.

Figure 3 is a top in Figure 1. v

Figure 4 is an enlarged top plan view'of the guiding and supporting means on the tank side wall, over which the flexible 'members'pa'ss- Figure 5 is a side elevational-view of said guid ing and supporting means. I I

Figure 6 is an end view, looking at the'i'nner end or left hand end of-said guiding and supportingmeansrand- Y v I 1 Figure '7 is an end view, looking at. the outer end or right hand end of said guidingand sup-' porting means.

T In the accompanying drawings, which illus trate the preferred form of myinvention, A designates theside wall of a tank or container of the kind used extensively'inthe 'oiliindustry' for storing oil and other volatile liquids,.and B'desig nates a floating roof that floats 'on'and-is sup ported by the liquida: in the'tank. The seal that is used to close the joint between the tank side wall and the peripheraledge" of thereof is not shown, as it forms no part of my present inven-' tion. In structures of the kind referred to there is a tendency for the roof to turn or rotate rela tively to th side wall of the tank, as the roof rises and falls, when the level of the liquid in the tank varies. My invention relates to a novel plan view of theparts shown means or mechanism for effectively preventin such rotational movement or turning movement of the roof, without relying on the 'useof co acting rigid guiding devices on the tank side wall and th roof. In'the particular form ofmy invem tion hereinillustrated saidmeans comprises two flexible members I= andl attached tothe'top side of the roof, at fairly widely separated points. as shown in Figurel, and disposeds'oals to lead Iii wardly from the motto a supporting and guiding means, designated as an entirety by the reference character C, carried by the'side 'w'allAfdf the tank and located substantially mid waythe two points at which the flexible members I and I are attached to the roof, therebycausing said flexible members to converge as they lead upwardly from the roof. Said flexibl members pass over or' through the guiding andsupporting means C on bars I and I, which are of equal length, are adjustably connected at their lower ends to the floating roof B, preferably by turnbuckles I, at points which are equidistant from the intersection with; the roof of a vertical line from the center of and tangent to the guiding device or bell 5 of the supporting means C. As shown in the drawings, the oppositely-inclined, flexible members I and I? are substantially parallel to the side wall of the tank, and they pass over the guiding device 5, thence over the sheave or roller 6, and thence downwardly to the weight 2 which holds said flexible members under tension. In order to prevent th weight 2 from swaying or swinging in the wind, said weight is guided by a taut cable 8, attached at its upper-end to a stationary bracket 3 that projects laterally from the tank side wall, and attached at its lower end to a laterally-projecting bracket III on the tank side wall, that serves as a stop which limits the downward movement of the weight 2, said bottom bracket I 0 being preferably located high enough above the surface of the ground to eliminate the possibility of the weight striking a person standing in close proximity to the tank side wall, in case the flexible members I and l break. a

In if 'talling the mechanism, the flexible mem-. be'rsI and I are attached to the roof, when it is in its lowermost position in the tank, theturnbuckles 'I being tightened until the tension in both of the flexible members I and I is about equal. Now, if as a roof moves upwardly, there are external forces exerted on the roof which tend to rotate the roof, the roof will try to rotate in that direction. If, for example, the roof moves slightly counterclockwise, or to the left, looking at Figure 1,, then the flexibl member I gets tighterand the flexible member l gets looser, because the first hypotenuseis lengthened, and the second shortened. The pull of the flexible member, I will be suflicient to set up a horizontal counter force at right angles to a roof radius through point P, which will be equal and opposite to the force, if applied atP, which was causing the rotation. The weight 2 is designed large enough so that the counter force will be larger than any predictable rotational force.

, As th roof moves upwardly, into the position shown in broken lines in Figure 1, the percentage of the total pull in the flexible member, which gives this counter force, is very much increased. The mast 3 takes torsion and bending, and as the two portions of the cross support 4 that project laterally in opposite directions from said mast are of equal length, the bending in the mast 3 is minimized. The cable 8 that serves as a guide for the weight 2 slants slightly, so that there will be arslight pull by the weight 2 on the guide 8 in all positions, which will hold the weight 2 steadier.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A liquid container provided with a side wall, a vertically-movable floating roof mounted in said container so as to be capable of turning or rotating slightly relatively to the side wall of the container, a horizontally-disposed support at the 1 top edge of the container side wall that projects inwardly and outwardly from said wall, a guide at the inner end of said support, a sheave at the outer end of said support, a pair of oppositely- JOHN H. WIGGINS. 

